Return-Path: Received: from mtain-mj12.r1000.mx.aol.com (mtain-mj12.r1000.mail.aol.com [172.21.164.96]) by air-db02.mail.aol.com (v129.4) with ESMTP id MAILINDB021-85ee4d2d5ee313d; Wed, 12 Jan 2011 02:57:23 -0500 Received: from post.thorcom.com (post.thorcom.com [195.171.43.25]) by mtain-mj12.r1000.mx.aol.com (Internet Inbound) with ESMTP id E1C2F380000B5; Wed, 12 Jan 2011 02:57:21 -0500 (EST) Received: from majordom by post.thorcom.com with local (Exim 4.14) id 1PcvYn-0006Ie-Fo for rs_out_1@blacksheep.org; Wed, 12 Jan 2011 07:56:01 +0000 Received: from [195.171.43.32] (helo=relay1.thorcom.net) by post.thorcom.com with esmtp (Exim 4.14) id 1PcvYm-0006IV-8D for rsgb_lf_group@blacksheep.org; Wed, 12 Jan 2011 07:56:00 +0000 Received: from filter02.i-online.fr ([195.200.78.9]) by relay1.thorcom.net with esmtp (Exim 4.63) (envelope-from ) id 1PcvYl-00056y-Gm for rsgb_lf_group@blacksheep.org; Wed, 12 Jan 2011 07:56:00 +0000 Received: from smtp.qtxt.dns-iol.com ([195.200.78.13]) by filter02.i-online.fr (IceWarp 10.0.7 (2010-02-10)) with ESMTP (SSL) id VIP14744 for ; Wed, 12 Jan 2011 08:55:44 +0100 Received: (qmail 5392 invoked by uid 507); 12 Jan 2011 08:55:48 +0100 Received: from unknown (HELO ?192.168.1.103?) (john.rabson@numeo.fr@217.67.155.178) by smtp.qtxt.dns-iol.com with SMTP; 12 Jan 2011 08:55:48 +0100 Mime-Version: 1.0 (Apple Message framework v1082) From: John Rabson X-Priority: 3 In-Reply-To: <0BF291DC12234E64A438CBF3CEDDB776@JimPC> Date: Wed, 12 Jan 2011 08:55:50 +0100 Message-Id: References: <201101111216460781.5C69093B@smtp2.numeo.fr> <0BF291DC12234E64A438CBF3CEDDB776@JimPC> To: rsgb_lf_group@blacksheep.org X-Mailer: Apple Mail (2.1082) X-Spam-Score: 0.0 (/) X-Spam-Report: autolearn=disabled,none Subject: LF: Re: RF ammeter question Content-Type: text/plain; charset=us-ascii Content-Transfer-Encoding: quoted-printable X-Spam-Checker-Version: SpamAssassin 2.63 (2004-01-11) on post.thorcom.com X-Spam-Level: X-Spam-Status: No, hits=0.0 required=5.0 tests=none autolearn=no version=2.63 X-SA-Exim-Scanned: Yes Sender: owner-rsgb_lf_group@blacksheep.org Precedence: bulk Reply-To: rsgb_lf_group@blacksheep.org X-Listname: rsgb_lf_group X-SA-Exim-Rcpt-To: rs_out_1@blacksheep.org X-SA-Exim-Scanned: No; SAEximRunCond expanded to false x-aol-global-disposition: G x-aol-sid: 3039400c89b84d2d5ee145cb X-AOL-IP: 195.171.43.25 Thanks Jim. With 1N5822 diodes response is within +/- 1 dB from 10 to 300= kHz. When I have the 1N4148s I will try them. 73 John F5VLF On 11 Jan 2011, at 14:47CET, James Moritz wrote: > Dear John, LF Group, >=20 > The 1N4007 and similar HV rectifiers have a notoriously slow recovery -= it is sometimes seen in amateur literature used as a PIN diode for this= reason. So one could expect problems using it as an RF rectifier. I have= made a number of versions of this ammeter circuit, using various small sw= itching diodes without problems at 136k and 500k. The Schottky rectifier= diodes you mentioned should have no problem with switching speed. They ha= ve quite high capacitance, but I guess this probably won't be a problem in= this relatively low impedance circuit. >=20 > Cheers, Jim Moritz > 73 de M0BMU